[Elecraft] Power supply V drop - was poor CW on K3S

[Fred Jensen]

"glass fuses"?  You want to avoid the in-line cylindrical cartridge 
fuses, the holders almost always have too much resistance.  Blade-type 
automotive fuses are much better ... much more contact surface, much 
more contact pressure, and a wiping action as you insert the fuse.  A 
drop of DeOxit on the blades as you insert the fuse will also help.  If 
this is a fixed installation and your power supply has some form of 
overcurrent protection [e.g. crowbar], there may be no need for any 
fuses in the power cable.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 4/25/2020 9:01 AM, Chuck Chandler wrote:
> Here's an update.
>
> I replaced the power cable running from the powerstrip with a 3-foot length
> with glass fuse holders in each leg.  I also adjusted the power supply to
> 14.50V at rest.  The K3S now shows 14.2V at rest.  At 100W TX the K3S shows
> 13.2V, so a 1 volt drop.  Way too much.
>
> The power supply voltage measured at the terminals drops from 14.50 to
> 14.44 for full power TX.  This seems too much, I had read the drop should
> be no more than 0.01V and this is 0.06V.
>
> So, suspecting the in line fuse holders I made up another cable with dual
> blade-fuse holders, which was worse.  TX voltage on the K3S display dropped
> to 12.9V.
>
> I'm suspecting my power supply is to blame - it's a TenTec 963, a
> re-branded Astron SS-30.  Alternatively, I have another commercial power
> cable with fuse holders I can cut down and try.
>
> Many thanks for all the help both here on the reflector and the direct
> emails from several fellows, and to Rich VE3KI for the on-air tests this
> morning!
>
> 73 de Chuck, WS1L
>